Mass measurement of graphene using quartz crystal microbalances
Abstract
Current wafer-scale fabrication methods for graphene-based electronics and sensors involve the transfer of single-layer graphene by a support polymer. This often leaves some polymer residue on the graphene, which can strongly impact its electronic, thermal, and mechanical resonance properties. To assess the cleanliness of graphene fabrication methods, it is thus of considerable interest to quantify the amount of contamination on top of the graphene. Here, we present a methodology for the direct measurement of the mass of the graphene sheet using quartz crystal microbalances (QCMs). By monitoring the QCM resonance frequency during removal of graphene in an oxygen plasma, the total mass of the graphene and contamination is determined with sub-graphene-monolayer accuracy. Since the etch-rate of the contamination is higher than that of graphene, quantitative measurements of the mass of contaminants below, on top, and between graphene layers are obtained. We find that polymer-based dry transfer methods can increase the mass of a graphene sheet by a factor of 10. The presented mass measurement method is conceptually straightforward to interpret and can be used for standardized testing of graphene transfer procedures in order to improve the quality of graphene devices in future applications.
Copyright and License
© 2019 Author(s). Published under license by AIP Publishing.
Acknowledgement
The authors thank Applied Nanolayers B.V. for supply and transfer of the single-layer graphene and Hugo Solera Licona for help with cleaning the crystals. This work is part of the research programme Integrated Graphene Pressure Sensors (IGPS) with Project No. 13307 which is financed by the Netherlands Organisation for Scientific Research (NWO). The research leading to these results also received funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 785219 Graphene Flagship. The authors acknowledge support from the Australian Research Council Centre of Excellence in Exciton Science (No. CE170100026) and the Australian Research Council Grants Scheme.
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Additional details
- ISSN
- 1077-3118
- Dutch Research Council
- 13307 IGPS
- European Research Council
- 785219
- Australian Research Council
- CE170100026